DAMASCUS, Syria (CNN) -- U.S. officials praised Syrian security forces for thwarting Tuesday's attack on the U.S. Embassy in Damascus despite the usually tense relationship with the Middle Eastern country.

The Syrians killed three attackers and apprehended a suspect outside the embassy after a car exploded near the walls of the American compound, the Syrian Information Ministry said.

"I do think the Syrians reacted to the attack in a way that helped to secure our people, and we very much appreciate that," U.S. Secretary of State Condoleezza Rice said while visiting Canada.

The Syrian forces met the attackers, and an embassy guard was killed battling them, the ministry said.

Fourteen people were wounded, including the suspect, an embassy policeman, a security worker and 11 civilians, among them two Iraqis and a Chinese official, according to Syria's state-run news agency, SANA.

China's state-run Xinhua News agency said a senior diplomat was slightly injured by shrapnel while standing on a rooftop in the nearby Chinese Embassy compound.

The Syrian Information Ministry said none of the embassy staff was wounded and the building was not damaged. As a precaution, the embassy and its affiliated school were closed until Thursday.

Usually about 30 Syrian guards are posted around the embassy 24 hours a day, said Imad Moustapha, Syria's ambassador to the United States.

Video from the scene showed the burned-out wreckage of a car and blood-soaked streets near the embassy, which is in a residential neighborhood of Damascus.

Syrian authorities found and dismantled another car bomb outside the embassy's walls. The vehicle was rigged with explosives, including some bombs made with propane gas tanks, according to Syria's state-run news agency and video from the scene.

Syrian authorities successfully defused other explosive devices found around the embassy, U.S. State Department spokesman Tom Casey said.

No one claimed responsibility for the attack, but Moustapha said Syrian officials suspect an al Qaeda offshoot group linked to other attacks in the country.

"In the past two years, low-scale terrorist attacks took place in Syria and some were related to a group called the Soldiers of Levant -- Jund al-Sham in Arabic," Moustapha told CNN.

"There might be a relation to this group in this attack, but things will be clarified very soon."

U.S. officials -- including Rice -- cautioned that it's too early to know for sure, pointing out several al Qaeda splinter groups operate in Syria.

"Clearly it was an organized terrorist attack on our embassy, but exactly who was responsible for it and ... who they might be affiliated with, what their motives are, are just things we'll have to look at as the days go on," Casey said.

American officials have accused Damascus of staging anti-U.S. demonstrations in the past, but they publicly thanked Syria for foiling Tuesday's attack.

The top U.S. diplomat at the embassy, Michael Corbin, telephoned Syria's deputy foreign minister and hailed the handling of the attack, according to a U.S. Embassy statement obtained by SANA.

White House press secretary Tony Snow said, "The U.S. government is grateful for the assistance Syria provided in going after the attackers. ... It illustrates the importance of the Syrians playing a constructive role in fighting terrorists."

U.S. still considers Syria terror sponsor

But Casey said the United States stands by its classification of Syria as a state sponsor of terror that allows certain groups to operate freely in Damascus.

He cited "ongoing concern" about a possible attack in Syria and among U.S. embassies in the Middle East because of deteriorating relations.

The United States pulled its ambassador to Syria following the February 2005 assassination of former Lebanese Prime Minister Rafik Hariri, an attack partly blamed on the Damascus government.

Moustapha said Syria's secular government also "is concerned about the rise of extremism and terrorism" in the region, blaming U.S. policies -- including its support of Israel's military action in Lebanon -- for fueling such groups.

CNN's John King, Andrea Koppel and Elise Labott contributed to this report.